Various electronic devices driven by batteries are used widely. A portable printer which is used to print a receipt and a check at a desired place is known as an example of such an electronic device. In addition, many portable information processing devices such as so-called hand held terminals are used.
In these electronic devices, there are many devices equipped with charge-type batteries. To charge the battery of the electronic device, the electronic device is connected to a charging apparatus (i.e., a battery charger) which functions as a power feeding device. The electronic device can be seen as a device to be charged, and includes a charging electrode. On the other hand, a terminal that contacts the electrode of the electronic device is provided in the battery charger.
A battery charger called a cradle is known as an example of the battery charger (see Japanese National Publication of International Patent Application No. 2014-521305). When the electronic device is charged, the electronic device is put on the cradle. Thereby, the electrode of the electronic device contacts the terminal provided in the cradle, and the charge to the electronic device is started.
Here, the cradle is not necessarily used for a charge function. A cradle having a data transmission function between the cradle (or other electronic device to which the cradle is connected) and the electronic device exists.